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On our York Furnace, the door switch will not cut the power when the blower door is opened. I'm guessing that it is spring loaded and the spring is stuck. Is it safe to try to repair it myself? Or should I call in a pro?

I'm sure I'll get blasted but why worry about it? I'd be glad if they didn't even exist. But if you have to ask is it safe that would indicate to me that you are wary of electricity. Just wear rubber boots and always keep one hand in your pocket.

Originally posted by casturbo Door switch?....yeah right, just bypass it. It's just another reason for a service call. Strange how only some units have them, while most others don't.

Gee, I want you working on my system.

Now you might do that on YOUR furnace, and I might do that on mine, but to advocate that on a public forum like this is just wrong. You have no idea of the OP's situation, furnace location, or who might have or get access. The funace is now running, the OP should call for service now, or at the least have it fixed when the system is inspected next cooling (or heating) season.

The blower door safety switch on fuel burning furnaces is NOT AN ELECTRICAL SAFETY DEVICE. It is a combustion safety device intended to prevent backdrafting of combustion gasses if the blower door falls off while the furnace is running.

In my opinion the switch is a relic left over from the days of standing pilot natural draft furnaces.
With todays furnaces that all have forced combustion and electronic ignition and safety controls, the blower safety switch is not needed, and is just another, often very anoying, piece that can fail.

However, the switch is still required to be installed by the manufacturer to get UL and GAMA listings, and I never permanently bypass them. If I find one that is stuck closed, I put a recommendation on my invoice that it be replaced as a CYA measure.

The damn things can be very frustrating when there is an intermittant problem with a furnace and no way to see the diagnostic codes with the door in place. I think the most frustrating ones are on stuff like Rheem/Ruud furnaces where they have a relativly sophisticated self diagnostic setup on the control board, but NO WAY TO ACCESS IT WITHOUT KILLING THE POWER TO THE BOARD. The newer units may have changed, but Rheem/Ruud furnaces have always been anoying because the diagnostic lights on the control board are are hidden by the blower door AND a cover over the control board compartment. Some other brands are like that too.